MAGMATIC ORIGIN FOR SEDIMENT-HOSTED Au DEPOSITS, GUIZHOU PROVINCE, CHINA: IN SITU CHEMISTRY AND SULFUR ISOTOPE COMPOSITION OF PYRITES, SHUIYINDONG AND JINFENG DEPOSITS

The southwest Guizhou Province, China, contains numerous sediment-hosted Au deposits with Au reserves greater than 700 tonnes. To date, the source of ore fluids that formed the Guizhou sediment-hosted Au deposits is controversial, hampering the formulation of genetic models. In this study, we selected the Shuiyindong and Jinfeng Au deposits, the largest strata-bound and fault-controlled deposits in Guizhou, respectively, for detailed research on pyrite chemistry and S isotope composition using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and laser ablation-multicollector-inductively coupled plasma-mass spectrometry ( LA- MC-ICP-MS), respectively. Petrography and pyrite chemistry studies distinguished five generations of pyrite. Among these, pre-ore pyrite 2 and ore pyrite are the most abundant types in the deposits. Pre-ore pyrite 2 is anhedral to euhedral and with similar to 2,639 ppm As and wider ranges of Cu, Sb, and Pb (<similar to 22-4,837 ppm, <similar to 6 to 532 ppm, and